In computing systems, such as desktop computers, portable or laptop computers, servers, and others, storage devices are used to store data and program instructions. A disk-based storage device is one type of storage device; disk-based storage device include magnetic disk drives (e.g., a floppy disk drive or hard disk drive) and optical disk drives (e.g., a CD or DVD drive). Disk-based storage devices have a relatively large storage capacity. However, disk-based storage devices offer slower read-write speeds when compared to operating speeds of other components of a computing system, such as microprocessors and other semiconductor devices. A solid state memory device is another type of storage device; solid state memory devices include dynamic random access memory (DRAM), static random access memory (SRAM), flash memory, and electrically erasable and programmable read-only memory (EEPROM). Although solid state memory devices offer relatively high read-write speeds, usually on the order of nanoseconds, they have relatively limited storage capacities.
With improvements in nanotechnology, other types of storage devices are being developed. One class of storage device utilizes one or more microscopic scanning probes to read and write to a storage medium. Storage of data in the storage medium is based on perturbations (dents) created by a tip of the probe in the surface of the storage medium. In one implementation, a dent represents a data bit “1,” and the lack of a dent represents a data bit “0.” Other types of perturbations in the storage medium surface that can be used to convey data include creating or altering the topographic features or composition of the storage medium, altering the crystalline phase of the medium, filling or emptying existing electronic states of the medium, creating or altering domain structures or polarization states in the medium, creating or altering chemical bonds in the medium, employing tunneling effects to move and/or remove atoms or charge to or from the medium, or storing/removing charge from a particular region.
When the probe tip encounters and enters a dent, the tip (usually about 400° C.) transfers heat to the storage medium, which causes the temperature of the probe tip to fall, which in turn causes the electrical resistance of the tip to decrease. This decrease in resistance, which is a relatively tiny amount, is measured by detection circuitry that determines the state of the data bit. Another technique for detecting the state of a data bit uses a piezoresistive element in the probe. When the probe tip encounters a dent, the cantilever of the probe deflects, which causes the resistance of the piezoresistive element to change. This change in resistance is measured by detection circuitry.
Cantilevered probes or cantilever beams are used to support the probe tip and provide the required Z-axis (vertical) flexibility to follow the topography of the media surface. When supported by a cantilever spring, the probe tip often tilts as it moves up and down in the vertical direction, so that proper contact is obtained at only a single height position of the probe. Any variation due to media surface imperfection in flatness, or in assembly tolerances, could prevent proper operation of the device. Various attempts at providing a better cantilever probe have been attempted.
The invention of the present disclosure provides an improved cantilever probe design that inhibits probe tip tilt and provides a more constant vertical flexibility.